Automatic ladling system for delivering molten metal from furnace to die casting machine

ABSTRACT

An automatic ladling system for a cold-chamber, low pressure type die casting machine and permanent molding machines including a housing which is adapted to be submerged in a reservoir of molten cast metal, and a dual piston pumping mechanism structured for synchronous actuation and located in the submerged housing, the first pumping device serving to pump a quantity of molten cast metal into the submerged housing, while the second pumping device is structured to pump molten cast metal from the housing through a gooseneck to the shot sleeve at the die cast injection chamber of a cold-chamber machine or directly into the casting mold in the case of low pressure or permanent molding.

Tlnited States Patent Lewis [451 Mar. 2%, 1972 [54] AUTOMATIC LADLINGSYSTEM FOR DELIVERING MOLTEN METAL FROM FURNACE TO DIE CASTING MACHINE[72] Inventor: Dong Sing Lewis, Toledo, Ohio [73] Assignee:Gerity-Schultz Corporation, Toledo, Ohio [22] Filed: Oct. 1, 1969 [21]Appl. No.: 862,794

[56] References Cited UNITED STATES PATENTS 3,056,178 10/1962 Jagielski..l64/318 X 3,430,685 3/1969 Drugowitsch ..l64/314 2,938,250 5/1960Larshetal. ..l64/3l6X Primary Examiner-Robert D. Baldwin Attorney-Wilson& Fraser 57 ABSTRACT An automatic ladling system for a cold-chamber, lowpressure type die casting machine and permanent molding machinesincluding a housing which is adapted to be submerged in a reservoir ofmolten cast metal, and a dual piston pumping mechanism structured forsynchronous actuation and located in the submerged housing, the firstpumping device serving to pump a quantity of molten cast metal into thesubmerged housing, while the second pumping device is structured to pumpmolten cast metal from the housing through a gooseneck to the shotsleeve at the die cast injection chamber of a cold-chamber machine ordirectly into the casting mold in the case of low pressure or permanentmolding.

4 Claims, 2 Drawing Figures PATENTEUmzs I972 SHEET 1 OF 2 FIG.

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NVE TER. DONG gm m IS WLLMQi/Mm ATTQRNEW AUTOMATIC LADLING SYSTEM FORDELIVERING MOLTEN METAL FROM FURNACE TO DIE CASTING MACHINE BACKGROUNDOF THE INVENTION This invention relates in general to an automaticladling system for a low pressure die casting machine, or thecoldchamber pressure casting machine or for permanent mold casting. Morespecifically, this invention relates to structural means adapted toensure that predetermined quantities of molten metal are consistentlyand uniformly delivered to the die cavities of a die casting machine. Inthis respect, this invention is based on a structural arrangement ofmultiple pumping devices to satisfy the requirement of consistency inthe amount of molten metal to be delivered to the die cavity.

A die casting machine of the type upon which this invention is based isusually comprised of a horizontally arranged base, having a holdingfurnace for molten metal, means adapted to pump molten metal submergedin the holding furnace, and a gooseneck having a passage therein whichprovides communication between the pumping means and the sleeve adjacentthe die cast cavity.

The die arrangement conventionally includes a vertically or horizontallypositioned die support, a plurality of spaced rods secured to one sideof the die support, on which is mounted for reciprocal movement amovable die support member. In addition, a cover die is mounted on therod side of the stationary die support and an ejector die is mounted onthe movable support on the side facing the cover die. The movable die isadapted to move toward the stationary die by way of hydraulic means in areciprocal manner, thus enabling the cover and ejector dies to be openedand closed pursuant to the die casting cycle.

Formerly, in the operation of cold chamber die casting machines, theshot" of molten metal was manually delivered from the melting chamber tothe shot sleeve at the end of the injection cylinder and at the entranceto the die cavity for the subsequent die casting process. In view of theinefficiency, poor product results, and dangers which this manual systemgenerated, semiautomatic and fully automatic means were conceived andbrought forth in the art for handling this system of delivering themolten metal to the sleeve of the die casting machine for injection intothe die cavity. At a still later phase, more fully automatic machineswere advanced, and in particular, the more modern automatic die castingmachines utilizes structural means for automatically metering the amountof molten metal to be delivered to the shot sleeve of the injectioncylinder near the die cavity.

However, the die casting machines with automatic metering means have nothad the requisite efficiency and effectiveness for delivering an exactpredetermined constant quantity of molten metal to the sleeve. For onematter, most of the structural approaches have been centered about useof automatic dipper mechanism, vacuum or air or gas pressuredisplacement means adapted to deliver to the shot sleeve an amount ofmolten metal greater than required by the capacity of the die cavityrunner and biscuit. As a consequence of such overcompensation, excessiveamounts of molten metal would be delivered to the die cast cavity,resulting in an undesirable situation, such as excessive large biscuit,as an excessive amount or insufficient amount of molten metal in the diecavity is not conducive to effective and efficient die casting.Furthermore, a single pump means often used to deliver molten metal tothe shot sleeve is often unable to deliver the exact and constant amountof molten metal required in the die cavity. This latter problem arisesfrom the fact that usually the shot-cylinder pump utilizes gravity flowor other inherent pressure sources to fill the shot cylinder due to thevarying metal level of the holding furnace. In particular, the gravityand pressure of the molten metal itself is used to fill the shotcylinder and, frequently, this combined gravity and force is notsufficient or substantial enough to fill the shot cylinder completely.Thus, very often the pressure or other means used to fill the shotcylinder will not perform sufficiently or properly to fill the primaryand only pump, thereby making it impossible for the pump to deliver tothe shot sleeve the predetermined amount of molten metal as called forby the pump capacity.

SUMMARY In view of the foregoing problems as existent in the art of diecasting machines, it is an object of this invention to provide anautomatic ladling system for a die casting machine which is fullyeffective in delivering predetermined and consistent quantities ofmolten metal to the sleeve of the die cavity;

A further object of this invention is to provide an improved ladlingsystem for a die casting machine and other casting methods which requireprecise metered amounts of molten metal for each cycle;

It is also an object of this invention to provide an automatic ladlingsystem for a die casting machine which is efficient in the usage ofmolten metal;

It is further the object of this invention to provide an automaticladling system which substantially eliminates the oxidation of moltenmetal; due to the nature of the reservoir oxides and inclusion arefloated and only clean metal is displaced to the shot sleeve or diecavity;

Still another object of the subject invention is to provide acomparatively safe automatic ladling system for a die casting machine;

Yet another object of the subject invention is to provide a moreproductive automatic ladling system for a die casting machine.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects of the subject inventionwill become apparent from the following description of the inventiontaken together with the accompanying drawings, in which:

FIG. 1 is a side elevational view of the die casting machineincorporating the subject invention, partly in cross section, showingthe pressure chamber situated in the holding furnace housing; and

FIG. 2 is an elevational view, partly in section, of the structureillustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT This invention involves anautomatic ladling system for a die casting machine and, in this regard,there is a horizontally disposed holding furnace having an exteriorhousing of some suitable refractory material, and securely disposed inthe mol ten metal held in this holding furnace is a pressure chamberhaving a two cylinder pumping structure contained within said pressurechamber. This pumping structure is adapted to pump the molten metal fromthe holding furnace into the pressure chamber and thence to a passagewaylocated in a gooseneck connected to the shot sleeve adjacent to the diecast cavity. Communicating with the sleeve is the end of a hydraulicinjection cylinder used as the final pressure means for injecting themolten metal into the die cast cavity from the sleeve.

Referring to the drawings, in which there is shown a specific embodimentof the subject invention, and referring particularly to FIG. 1, aholding furnace or molten metal reservoir 10 of substantially horizontaldisposition is shown. The holding furnace 10 contains molten metal at alevel generally indicated by reference numeral 12, and includes heatingmeans (not shown) for maintaining the metal in a molten state. The wallsof the holding furnace 10 are formed of refractory material which iscapable of withstanding high temperatures over relatively long periodsof time.

Fixedly secured in the holding furnace 10 is a multichambered housing 14having vertical spaced apart sidewalls l6 and 18, which functions todraw molten metal from the holding furnace 10 for pumping the moltenmetal to the die cavities. Connected to the bottom of the sidewall 16and communicating with the interior of housing 14 is a gooseneck 20,having an internal passageway 22. The upper end of the gooseneck 20 isconnected to a spout 24 which communicates with a sleeve 25 at theentrance of the die cavity (not shown). Within the housing 14 are twovertically disposed cylinders 26 and 28, which define an intermediatelydisposed chamber 30. Both cylinder 26 and 28 have wall linings made ofgraphite or other suitable refractory material for retaining the moltenmetal in its heated state. Disposed within each of the cylinders 26 and28 are pistons 32 and 34, respectively, which are adapted to reciprocatepredetermined distances therein.

Cylinder 28 is typically of a larger diameter than cylinder 26.Consequently, the volume of molten metal which can be pumped by cylinder28 is greater than the volume of molten metal which can be pumped bycylinder 26.

Extending from the upper portions of pistons 32 and 34 are verticallydisposed rods 36 and 38, respectively, which are fixedly secured to thepistons for integral movement therewith. Rods 36 and 38 are, in turn,fixedly secured at their upper ends to a horizontally disposed crossbrace member 40. More particularly, the rod 36 is secured to one end ofthe cross brace 40 by a conventional locking method, while rod 38 issecured to the opposite end by a similar conventional locking.

Suitably fastened to the cross brace 40 is vertically disposed pistonrod 42 of a fluid motor 44. The fluid motor 44 is fixedly secured insuch a fashion that, upon actuation thereof, the piston rod 42 can movethe cross brace 40 relative to the furnace 10.

It will be readily apparent from the foregoing description that wheneverthe fluid motor 44 is actuated to move the piston rod 42 downwardly,cross brace 40 will be caused to move downwardly and consequently, therods 36 and 38 will travel downwardly to the same vertical extent,simultaneously effecting downward movement of the pistons 32 and 34 incylinders 26 and 28, respectively. It can be seen that the pistons ineach cylinder will travel downwardly simultaneously and to the samevertical extent, resulting in the same relative displacement in eachcylinder 26 and 28.

Centrally disposed between the cylinders 26 and 28 in the housing 14there is a chamber 50. Communicating between the lower end of thecylinder 28 and the upper portion of chamber 50 is a generallyvertically disposed passageway 52. Additionally, the cylinder 28 isprovided with an inlet port 56 leading from the interior of the furnacethrough the vertical wall 18 of the housing 14 directly to the inside ofcylinder 28. An inlet port 58 is provided to establish communicationbetween the central chamber 50 and the interior of the cylinder 26.

The gooseneck is provided with an internal passageway 22 which providescommunication between an outlet port 60 of the cylinder 26 and the inletof the spout 24. Spout 24 may be heated electrically, for example, toinsure a smooth flow of molten metal therethrough. The spout 24 leadsdirectly to the sleeve ofa die cavity ofa die casting machine.

In operation, molten metal from holding furnace 10 is drawn into chamber14 through inlet port 56 by the partial vacuum effect created upon thewithdrawal of piston 34. Subsequently, when hydraulic plunger 38 islowered, molten metal will be forced from cylinder 28 into thepassageway 52 and thence into central chamber 50. On the followingstroke, the raising of the piston 32 in the cylinder 26 causes themolten metal in central chamber 50 to flow through inlet port 58 andinto the cylinder 26. When piston 32 is lowered after molten metalenters the cylinder 26, the inlet port 58 is closed by the piston 32 andthe molten metal will be forced from cylinder 26 upward throughpassageway 22 of the gooseneck 20 to the spout 24 and thence into theassociated die cavity.

The structural relationship of having cylinder 28 larger than cylinder26 ensures that the interior of the cylinder 28, and thus, the centralchamber 50 will always have more molten metal than the capacity ofcylinder 26, which injects the molten metal into the die cavity. Thiswill ensure that cylinder 26 is always full to capacity or maintain aconstant metal level 12 to inject a constant amount of molten metal intothe associated die cavity Thus, the die cavity will always be filledwith a consistent exact amount of molten metal during each duty cycle,regardless of metal level 12 in furnace 10.

It can thus be seen by the structural arrangement of the dual pumpingarrangement in the housing 14 that the cylinder 26 will always be filledcompletely because the molten metal drawn into the cylinder 26 will bereceived from the quiescent reservoir of molten metal in the centralchamber 50. Any excess metal displaced by the piston 34 into the chamber50 is overflowed off by overflow grooves 66, thus maintaining a constantmetal level in the reservoir chamber 50.

It will be understood that the main body portion of the housing 14 ispreferably formed of a suitable ceramic refractory material wherein theinternal walls of the cylinders 26 and 28 are provided with sleeves ofwear resistent material to provide the necessary sealing fit with theexternal walls of the pistons 32 and 34, respectively.

According to the provisions of the patent statutes, 1 have explained theprinciples and mode ofmy invention and have illustrated and describedwhat I now consider to represent its best embodiment. However, I desireto have it understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically illustratedand described.

What I claim is:

1. A system for delivering molten metal from a molten metal furnace to acasting machine comprising:

a housing mounted within said furnace and adapted to be at leastpartially submerged below the normal level of the molten metal in thefurnace, said housing comprising adjacent first, second, and thirdchambers;

said first chamber having a larger volume than said third chamber;

first inlet means in said housing disposed to be beneath the normallevel of the molten metal in said furnace and providing communicationbetween the molten metal and said first chamber;

closed passageway means between and extending from the lower portion ofsaid first chamber to the upper portion of said second chamber andproviding communication between said first and second chambers, saidpassageway means having a substantially smaller volume than said firstchamber;

second inlet means in said third chamber disposed to be beneath thelevel of said passageway outlet into said second chamber and providingcommunication between said second and third chambers;

outlet means in said housing providing communication between said thirdchamber and the casting machine;

and pumping means in said first and third chambers, said pumping meansbeing adapted to move vertically with simultaneous reciprocal movementand the same vertical displacement;

whereby molten metal can be pumped through said first and third chamberswith each downward stroke of said pumping means, and said second chambercan be constantly maintained at full capacity with molten metal, andthereby effectively delivering molten metal from the furnace to thecasting machine.

2. The invention defined in claim 1 wherein said passageway outlet isdisposed to be above the normal level of the molten metal in thefurnace.

3. The invention defined in claim 1 wherein said pumping means consistsof a piston in the first and third chambers.

4. The invention defined in claim 3 wherein said pumping means includesa pressure fluid motor for effecting simultaneous reciprocal movement ofthe pistons.

1. A system for delivering molten metal from a molten metal furnace to acasting machine comprising: a housing mounted within said furnace andadapted to be at least partially submerged below the normal level of themolten metal in the furnace, said housing comprising adjacent first,second, and third chambers; said first chamber having a larger volumethan said third chamber; first inlet means in said housing disposed tobe beneath the normal level of the molten metal in said furnace andproviding communication between the molten metal and said first chamber;closed passageway means between and extending from the lower portion ofsaid first chamber to the upper portion of said second chamber andproviding communication between said first and second chambers, saidpassageway means having a substantially smaller volume than said firstchamber; second inlet means in said third chamber disposed to be beneaththe level of said passageway outlet into said second chamber andproviding communication between said second and third chambers; outletmeans in said housing providing communication between said third chamberand the casting machine; and pumping means in said first and thirdchambers, said pumping means being adapted to move vertically withsimultaneous reciprocAl movement and the same vertical displacement;whereby molten metal can be pumped through said first and third chamberswith each downward stroke of said pumping means, and said second chambercan be constantly maintained at full capacity with molten metal, andthereby effectively delivering molten metal from the furnace to thecasting machine.
 2. The invention defined in claim 1 wherein saidpassageway outlet is disposed to be above the normal level of the moltenmetal in the furnace.
 3. The invention defined in claim 1 wherein saidpumping means consists of a piston in the first and third chambers. 4.The invention defined in claim 3 wherein said pumping means includes apressure fluid motor for effecting simultaneous reciprocal movement ofthe pistons.